Drawdown and turbidity: hayward reservoir, mission, british columbia

In partnership with Hemmera Envirochem Ltd. changes to water quality during test drawdowns in Hayward Reservoir, near Mission, B.C. were examined. This monitoring was part of planning water quality protection measures to be applied during drawdown that was needed to accommodate construction during seismic upgrade of the Ruskin Dam and associated powerhouse. Water quality protection was needed because Hayward Reservoir is a source of drinking water for nearby communities and the reservoir and downstream river provide important fish habitat needing protection under the Canada Fisheries Act. The drinking water is filtered prior to distribution. Hayward Reservoir is ultra-oligotrophic meaning it has very low nutrient concentrations and low phytoplankton biomass. Nutrient concentrations and phytoplankton biomass did not change during drawdown. Extreme turbidity caused by fluvial erosion within newly exposed stream channels and smaller wave-driven turbidity along shorelines at drawdown was temporary. Due to rapid settlement of particles in stream deltas and littoral zones, there was only a small change in turbidity within the reservoir. Filtration was effective and allowed continuous use of the reservoir water for consumption during drawdown.

 

Client:                   BC Hydro

Funding:              BC Hydro

Sector:                  Reservoirs and lakes

Status:                  Completed 2011